1. Field of Invention
The present invention relates to an industrial field of a motor vehicle wiper apparatus to be installed on motor vehicles such as passenger cars for private use, buses and trucks to wipe their windshields (or window) surfaces.
2. Description of Related Art
In general, in this type of wiper apparatus for motor vehicles, as shown in FIGS. 4A and 4B, a pivot (wiper shaft) 12 is borne by a pivot holder (sleeve) 11 which is fixedly secured to a vehicle body side. The pivot 12 is rotatable around the axis of the pivot holder 11. A lower end portion of the pivot 12 is fixedly secured to a rocking link 13 which is connected to a wiper motor. An upper end portion of the pivot 12 is fixed to a proximal portion of a wiper arm. This structure causes a reciprocating wiping oscillation of the wiper arm accompanying a rotational drive of the wiper motor.
Furthermore, this apparatus requires that the pivot 12 be positioned and fixed with respect to the pivot holder 11 to prevent the pivot 12 from falling out of the pivot holder 11. For this reason, a design disclosed in Japanese Unexamined Utility Model Publication No. 4-50551 has been proposed, where a flat washer 14 is placed against a tip portion of a pivot 12 and a retainer ring 15. A portion of this retainer ring 15 is cut and the entire retainer ring 15 is fitted in an engaging groove 12a in an outer circumference of the pivot 12. The position of the engaging groove 12a corresponds to the top surface of the flat washer 14 so that the retainer ring 15 comes into contact with the flat washer 14 to retain pivot 12 on the pivot holder 11.
However, when this apparatus is incorporated into a vehicle body, the pivot 12 and the pivot holder 11 are treated as a single wiper pivot assembly. After the assembly is installed on a vehicle body, a wiper arm is set thereto. In this instance, during the conveyance of the aforesaid wiper pivot assembly, there is the risk that, for example, a thread groove 12b in the tip portion of the pivot 12 collides against other components and deforms.
To cope with such an event, the pivot 12 is taken out from the pivot holder 11 and replaced with a new pivot 12. However, removing the pivot 12 requires disconnecting the retainer ring 15. Removing the retainer ring 15 is a problem because the retainer ring 14 is not only made of a spring steel but is also small and fitted in the engaging groove 12a. Therefore, special tools which require a delicate touch are needed.
In addition, since some parts of the wiper apparatus, such as the wiper arm and the pivot, appear outside the vehicle body, they can directly undergo external shocks. In some cases the shock reaches, not only the wiper arm, the pivot and the pivot holder, but also the entire wiper apparatus. The shock can affect the fit of the wiper apparatus to the vehicle body and may even affect the vehicle body.
In this invention, a pivot rotatably extends from the vehicle body interior side to the exterior through a pivot holder that is fixed integrally onto a vehicle body. The pivot holds a wiper arm at its penetrating tip portion. An engaging groove is made in a pivot holder penetrating portion of the pivot and a retainer ring is fitted in the engaging groove to retain the pivot on the pivot holder. The retainer ring clamps down into the engaging groove. The retainer ring has ends which can be forced apart. The engaging groove is notched with an inclined groove side surface toward the tip of the pivot.
In this way, releasing the pivot from the pivot holder is a simple operation. Additionally, if an external large shock is received, the retainer ring disconnects from the engaging groove of the pivot, and the pivot absorbs the shock by moving downwardly from the pivot holder. Thus, the shock does not affect the entire wiper apparatus or the vehicle body. This decreases the number of parts to be replaced or repaired which reduces cost.